Blowing agent compositions of hydrofluoroolefins and hydrochlorofluoroolefins

ABSTRACT

The present invention relates to blowing agent compositions comprising (1) at least one hydrofluoroolefin (HFO) and (2) at least one hydrochlorofluoroolefin (HCFO) used in the preparation of foamable thermoplastic compositions. The HFOs of component (1) include, but are not limited too, 3,3,3-trifluoropropene (HFO-1243zf), 1,2,3,3,3-pentafluoropropene (HFO-1225ye), cis- and/or trans-1,3,3,3-tetrafluoropropene (HFO-1234ze), and 2,3,3,3-tetrafluoropropene (HFO 1234yf), and mixtures thereof. The HCFOs of component (2) include, but are not limited to, 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and mixtures thereof. The blowing agent compositions are useful in the production of low density insulating foams with improved k-factor.

This application is a divisional of U.S. application Ser. No. 14/243,048filed Apr. 2, 2014, which is a divisional of U.S. application Ser. No.13/914,711 filed Jun. 11, 2013, which issued as U.S. Pat. No. 8,772,364on Jul. 8, 2014, which is a continuation-in-part of U.S. applicationSer. No. 12/532,238 filed Sep. 21, 2009, abandoned, which claimedpriority to International application serial number PCT/US08/58594 filedMar. 28, 2008 which application designated the United States and whichclaimed priority to U.S. provisional application Ser. No. 60/908,762filed Mar. 29, 2007 all of which are incorporated herein by reference.

SUMMARY OF INVENTION

The present invention relates to blowing agent compositions comprising(1) at least one hydrofluoroolefin (HFO) and (2) at least onehydrochlorofluoroolefin (HCFO) used in the preparation of foamablethermoplastic compositions. The HFOs of component (1) include, but arenot limited too, 3,3,3-trifluoropropene (HFO-1243zf),1,2,3,3,3-pentafluoropropene (HFO-1225ye), cis- and/ortrans-1,3,3,3-tetrafluoropropene (HFO-1234ze), and2,3,3,3-tetrafluoropropene (HFO 1234yf), and mixtures thereof. The HCFOsof component (2) include, but are not limited to,1-chloro-3,3,3-trifluoropropene (HCFO-1233zd),2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), dichloro-fluorinatedpropenes, and mixtures thereof. The blowing agent compositions areuseful in the production of low density insulating foams with improvedk-factor.

BACKGROUND OF INVENTION

With the continued concern over global climate change there is anincreasing need to develop technologies to replace those with high ozonedepletion potential (ODP) and high global warming potential (GWP).Though hydrofluorocarbons (HFC), being non-ozone depleting compounds,have been identified as alternative blowing agents tochlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) in theproduction of thermoplastic foams, they still tend to have significantGWP.

Hydrofloroolefins, such as HFO-1243zf, (cis/trans)-HFO-1234ze,HFO-1234yf, and (E/Z)-HFO-1225ye, have been identified as potential lowGWP blowing agents for the production of thermoplastic foams, includingextruded polystyrene foams for thermal insulation.

It was discovered that blowing agent compositions comprising at leastone hydrofluorolefin with at least one hydrochlorofluoroolefin canpermit the production of lower density, closed-cell foam with goodk-factor which will be particularly useful for thermal insulating foams.This invention may also permit the production of low density,closed-cell foams with enlarged, controlled cell size.

WO 2004/037913, WO 2007/002703, and US Pat. Publication 2004119047disclose blowing agents comprising halogenated alkenes of genericformula that would include numerous HFOs and HCFOs, among many othermaterials including brominated and iodinated compounds. The specificcombination of HFOs with HCFOs in blowing agent compositions is notdisclosed. Specific examples are shown for blowing agent compositionsfor foaming polystyrene comprising HFOs, specifically HFO-1234ze andHFO-1234yf, either alone or in combination with an HFC, and blowingagent compositions for PUR foaming comprising HCFO-1233zd. No examplesof blowing agents combinations comprising HFOs and HCFOs are disclosed.

GB 950,876 discloses a process for the production of polyurethane foams.It discloses that any suitable halogenated saturated or unsaturatedhydrocarbon having a boiling point below 150° C., preferably below 50°C., can be used as the blowing agent. Trichlorofluoroethene,chlorotrifluoroethene, and 1,1-dichloro-2,2-difluoroethene are disclosedin a list of suitable blowing agents along with 3,3,3-trifluoropropene.Hydrochlorofluoropropenes are not specifically disclosed nor are longerchain HCFOs nor other HFOs besides 3,3,3-trifluoropropene. There is nodisclosure related to blowing agents for thermoplastic foaming, nor arethe benefits of HCFOs in thermoplastic foaming mentioned, nor are thebenefits of blowing agent combinations comprising HCFOs and HFOs.

CA 2016328 discloses a process for preparing closed-cell, polyisocyanatefoam. Disclosed are organic compound blowing agents includinghalogenated alkanes and alkenes, where the alkene is propylene, and thehalogenated hydrocarbons can be chlorofluorocarbons. Among the manyexemplary compounds listed are specific chlorofluoroethylenes containing1 chlorine and from 1 to 3 fluorines along with specificpentafluoropropene, tetrafluoropropene, and difluoropropene.Hydrochlorofluoropropenes are not specifically disclosed nor are longerchain HCFOs. There is no disclosure related to blowing agents forthermoplastic foaming, nor are the benefits of HCFOs in thermoplasticfoaming mentioned, nor are the benefits of blowing agent combinationscomprising HCFOs and HFOs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of total blowing agent content versus foam density forexamples 19-48.

DETAILED DESCRIPTION OF INVENTION

The present invention relates to the use of blowing agents withnegligible ozone-depletion and low GWP comprising (1) at least onehydrofluoroolefin (HFO) and (2) at least on hydrochlorofluoroolefin(HCFO). The present invention discloses blowing agent and foamable resincompositions useful for the production of thermoplastic foams, which maybe polystyrene, polyethylene, polypropylene, or mixtures thereof, withdecreased density and improved k-factor that can be used as insulatingfoams. In a preferred embodiment of this invention the HFO in component(1) is a C3 through C5 fluorinated alkene such as 3,3,3-trifluoropropene(HFO-1243zf); (cis and/or trans)-1,3,3,3-tetrafluoropropene(HFO-1234ze), particularly the trans isomer; 2,3,3,3-tetrafluoropropene(HFO-1234yf); (cis and/or trans)-1,2,3,3,3-pentafluoropropene(HFO-1225ye) and mixtures thereof. The HCFO of component (2) ispreferably (cis and/or trans)-1-chloro-3,3,3-trifluoropropene(HCFO-1233zd), particularly the trans isomer,2-chloro-3,3,3-trifluoropropene (HCFO-1233xf),1,1-dicloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3-trifluoropropene,and mixtures thereof.

The blowing agent composition of the present invention may furthercomprise co-blowing agents such as hydrofluorocarbons, alkanes, carbondioxide, methyl formate, inert gases, atmospheric gases, alcohols,ethers, fluorinated ethers, unsaturated fluorinated ethers, ketones,fluoroketones, water, and mixtures thereof. The hydrofluorocarbons maybe selected from HFC-32, HFC-161, HFC-152, HFC-152a, HFC-143, HFC-143a,HFC-134, HFC-134a, HFC-125, HFC-245fa, HFC-365mfc, HFC-227ea, ormixtures thereof. The alkanes may be selected from propane, butane,pentane, such as n-pentane, cyclopentane, iso-pentane or mixturesthereof, or hexane. The alcohols may be selected from ethanol,iso-propanol, butanol, ethyl hexanol, methanol, or mixtures thereof. Theethers may be selected from dimethyl ether, diethyl ether, methylethylether, or mixtures thereof. The ketones may be selected from acetone,methyl ethyl ketone, or mixtures thereof. In addition, the blowing agentcomposition of the present invention may further comprise additives suchas dyes, pigments, cell-controlling agents, fillers, antioxidants,extrusion aids, stabilizing agents, antistatic agents, fire retardants,IR attenuating agents, thermally insulating additives, plasticizers,viscosity modifiers, impact modifiers, gas barrier resins, carbon black,surfactants, and mixtures thereof.

Another embodiment of this invention are foamable resin compositionscontaining greater than about 1 parts per hundred (pph) and less thanabout 100 pph of the blowing agent composition with respect to resin,preferably greater than about 2 pph and less than about 40 pph, morepreferably greater than about 3 pph and less than about 25 pph, and evenmore preferably greater than about 4 pph and less than about 15 pph ofthe blowing agent composition with respect to resin.

Another embodiment of this invention is a thermoplastic foam comprisinga blowing agent with negligible ozone-depletion and low GWP comprisingat least one hydrofluoroolefin (HFO) and at least onehydrochlorofluoroolefin (HCFO). The thermoplastic foams of the presentinvention exhibit a decreased density and improved k-factor and can beused as insulating foams. In a preferred embodiment of this inventionthe blowing agent can comprise an HFO component selected from3,3,3-trifluoropropene (HFO-1243zf); (cis and/ortrans)-1,3,3,3-tetrafluoropropene (HFO-1234ze), particularly the transisomer; 2,3,3,3-tetrafluoropropene (HFO-1234yf); (cis and/ortrans)-1,2,3,3,3-pentafluoropropene (HFO-1225ye) and mixtures thereof.The HCFO component of the blowing agent can be selected from (cis and/ortrans)-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), particularly thetrans isomer, 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf),1,1-dicloro-3,3,3-trifluoropropene, 1,2-dichloro-3,3,3-trifluoropropene,and mixtures thereof. In one embodiment of the present invention, thethermoplastic foam has a density below about 50 kg/m³ at a blowing agentloading of from about 7 to about 13 wt %, and preferably a density ofbetween about 38 and 50 kg/m³ at a blowing agent loading of from about 7to about 13 wt %. In another embodiment of this invention, thethermoplastic foam has a density of less than about 70 kg/m³, preferablyfrom about 24 kg/m³ to about 50 kg/m³ and most preferably from about 38kg/m³ to about 50 kg/m³. In another embodiment of this invention, thethermoplastic foam is a closed-cell foam, preferably with an open-cellcontent of less than about 20%, more preferably less than about 10%. Inanother embodiment of this invention, the thermoplastic foam has a finecell structure, preferably with an average cell size of from about 0.05mm to about 1.0 mm, more preferably from about 0.05 mm to about 0.5 mm.

In another embodiment of this invention, the blowing agent comprisesfrom about 1 to about 99 wt % of the HCFO component, preferably fromabout 2 to about 90 wt % of the HCFO component. In embodiment of thisinvention, the blowing agent comprises more than about 10 wt/% of theHCFO component. In embodiment of this invention, the blowing agentcomprises more than about 20 wt % of the HCFO component. In embodimentof this invention, the blowing agent comprises more than about 30 wt %of the HCFO component. In embodiment of this invention, the blowingagent comprises less than about 70 wt % of the HCFO component. Inembodiment of this invention, the blowing agent comprises less thanabout 65 wt %/o of the HCFO component. In embodiment of this invention,the blowing agent comprises less than about 60 wt % of the HCFOcomponent. In embodiment of this invention, the blowing agent comprisesless than about 50 wt % of the HCFO component. In another embodiment ofthe this invention, the blowing agent comprises more than about 20 wt %of the HFO component. In another embodiment of this invention, theblowing agent comprises more than about 30 wt % of the HFO component. Inanother embodiment of this invention, the blowing agent comprises morethan about 40 wt % of the HFO component. In another embodiment of thisinvention, the blowing agent comprises more than about 50 wt % of theHFO component. In another embodiment of this invention, the blowingagent comprises more than about 60 wt % of the HFO component. In anotherembodiment of this invention, the blowing agent comprises more thanabout 70 wt % of the HFO component. In another embodiment of thisinvention, the blowing agent comprises more than about 90 wt % of theHFO component. In another embodiment of this invention, the blowingagent comprises from about 50 wt % to about 98 wt % of the HFOcomponent.

The process for preparing a foamed thermoplastic product, which may bepolystyrene, polyethylene, polypropylene, or mixtures thereof, is asfollows: Prepare a foamable polymer composition by blending togethercomponents comprising foamable polymer composition in any order.Typically, prepare a foamable polymer composition by plasticizing apolymer resin and then blending in components of a blowing agentcomposition at an initial pressure. A common process of plasticizing apolymer resin is heat plasticization, which involves heating a polymerresin enough to soften it sufficiently to blend in a blowing agentcomposition. Generally, heat plasticization involves heating athermoplastic polymer resin near or above its glass transitiontemperature (Tg), or melt temperature (Tm) for crystalline polymers.

A foamable polymer composition can contain additional additives such asnucleating agents, cell-controlling agents, dyes, pigments, fillers,antioxidants, extrusion aids, stabilizing agents, antistatic agents,fire retardants, IR attenuating agents and thermally insulatingadditives. Nucleating agents include, among others, materials such astalc, calcium carbonate, sodium benzoate, and chemical blowing agentssuch azodicarbonamide or sodium bicarbonate and citric acid. IRattenuating agents and thermally insulating additives can include carbonblack, graphite, silicon dioxide, metal flake or powder, among others.Flame retardants can include, among others, brominated materials such ashexabromocyclodecane and polybrominated biphenyl ether.

Foam preparation processes of the present invention include batch,semi-batch, and continuous processes. Batch processes involvepreparation of at least one portion of the foamable polymer compositionin a storable state and then using that portion of foamable polymercomposition at some future point in time to prepare a foam.

A semi-batch process involves preparing at least a portion of a foamablepolymer composition and intermittently expanding that foamable polymercomposition into a foam all in a single process. For example, U.S. Pat.No. 4,323,528, herein incorporated by reference, discloses a process formaking polyolefin foams via an accumulating extrusion process. Theprocess comprises: 1) mixing a thermoplastic material and a blowingagent composition to form a foamable polymer composition; 2) extrudingthe foamable polymer composition into a holding zone maintained at atemperature and pressure which does not allow the foamable polymercomposition to foam; the holding zone has a die defining an orificeopening into a zone of lower pressure at which the foamable polymercomposition foams and an openable gate closing the die orifice; 3)periodically opening the gate while substantially concurrently applyingmechanical pressure by means of a movable ram on the foamable polymercomposition to eject it from the holding zone through the die orificeinto the zone of lower pressure, and 4) allowing the ejected foamablepolymer composition to expand to form the foam.

A continuous process involves forming a foamable polymer composition andthen expanding that foamable polymer composition in a non-stop manner.For example, prepare a foamable polymer composition in an extruder byheating a polymer resin to form a molten resin, blending into the moltenresin a blowing agent composition at an initial pressure to form afoamable polymer composition, and then extruding that foamable polymercomposition through a die into a zone at a foaming pressure and allowingthe foamable polymer composition to expand into a foam. Desirably, coolthe foamable polymer composition after addition of the blowing agent andprior to extruding through the die in order to optimize foam properties.Cool the foamable polymer composition, for example, with heatexchangers.

Foams of the present invention can be of any form imaginable includingsheet, plank, rod, tube, beads, or any combination thereof. Included inthe present invention are laminate foams that comprise multipledistinguishable longitudinal foam members that are bound to one another.

EXAMPLES Examples 1-8 Solubility and Diffusivity of Gases in Polystyrene

The solubility and diffusivity of gases in polystyrene resin wasmeasured using capillary column inverse gas chromatography (cc-IGC) asdescribed in: Hadj Romdhane, Ilyess (1994) “Polymer-Solvent Diffusionand Equilibrium Parameters by Inverse Gas-Liquid Chromatography” PhDDissertation, Dept. of Chem. Eng., Penn State University. and Hong S U,Albouy A, Duda J L (1999) “Measurement and Prediction of Blowing AgentSolubility in Polystyrene at Supercritical Conditions” Cell Polym18(5):301-313.

A 15 m long, 0.53 mm diameter GC capillary-column was prepared with a 3micron thick polystyrene internal film coating. The column was installedinto a Hewlet Packard 5890 Series II Gas Chromatograph with flameionizer detector. Elution profiles for gases being tested were analyzedaccording the method outlined in the reference, using methane as thereference gas. The results give the diffusion coefficient of the gasthrough the polymer, Dp, and the solubility of the gas in the polymer interms of the partition coefficient, K, which is the ratio of theconcentration of the gas in the polymer phase to the concentration inthe vapor phase. As such, the greater the value of K for a particulargas in the resin the greater its solubility in that resin.

Table 1 shows the partition coefficient and diffusivity values forseveral gases in polystyrene at 140° C. Comparative examples 1 and 2show the solubility and diffusivity of two well studied blowing agentsin polystyrene: HCFC-142b (1-chloro-1,1-difluoroethane) and HFC-134a(1,1,1,2-tetrafluoroethane). Examples 3-6 show the solubility anddiffusivity of selected HFOs in polystyrene: HFO-1243zf(3,3,3-trifluoropropene), HFO-1234ze (1,3,3,3-tetrafluoropropene),HFO-1234yf (2,3,3,3-tetrafluoropropene), HFO-1225ye(1,2,3,3,3-pentafluoropropene). Examples 7 and 8 show the solubility anddiffusivity of trans-HCFO-1233zd (1-chloro-3,3,3-trifluoropropene) andHCFO-1233xf (2-chloro-3,3,3-trifluoropropene),

The good solubility and favorable diffusivity of the HCFOs inpolystyrene indicate that they should be effective coblowing agentsand/or processing aids for the production of thermoplastic foams usingHFO blowing agents. The solubility of the HCFOs in polystyrene issufficient to provide useful plasticization of the thermoplastic resinto assist in foaming. As can be seen, HCFO-1233xf has a solubility inpolystyrene comparable to that of HCFC-142b.

TABLE 1 Partition Coefficient and Diffusivity of Gases in Polystyrene at140° C. by Inverse Gas Chromatography Bp Mw Dp Example Gas (° C.)(g/mol) K (cm²/s) 1 HCFC-142b −9.8 100.49 1.249 2.61E−08 2 HFC-134a−26.1 102.02 0.397 3.40E−08 3 HFO-1243zf −22 98.05 0.544 2.95E−08 4HFO-1234ze −16 114.04 0.423 3.09E−08 5 HFO-1225ye −18 132.03 0.3122.44E−08 6 HFO-1234yf −28.5 114.04 0.275  >2E−08 7 HGFO-1233zd 20.5130.5 2.326 1.72E−08 8 HCFO-1233xf 15 130.5 1.475 1.67E−08

Examples 9-18

Extruded polystyrene foam was produced using a counter-rotating twinscrew extruder with internal barrel diameters or 27 mm and a barrellength of 40 diameters. The screw design was suitable for foamingapplications. The pressure in the extruder barrel was controlled withthe gear pump and was set high enough such that the blowing agentdissolved in the extruder. The extruder die for examples 10-18 was anadjustable-lip slot die with a gap width of 6.35 mm. For example 1, thedie was a 2 mm diameter strand die with a 1 mm land length. Two gradesof general purpose polystyrene were used for the extrusion trials andfed to the extruder at rates of either 2.27 or 4.54 kg/hr (5 or 10lb/hr). Blowing agents were pumped into the polystyrene resin melt at acontrolled rate using high pressure delivery pumps. In the extruder, theblowing agent is mixed and dissolved in the resin melt to produce anexpandable resin composition. The expandable resin composition is cooledto an appropriate foaming temperature and then extruded from the diewhere the drop in pressure initiates foaming. Talc was used as anucleating agent and was pre-blended with polystyrene to make amasterbatch of 50 wt % talc in polystyrene. Beads of this masterbatchwere mixed with polystyrene pellets to achieve 0.5 wt % talc in eachexperiment.

The density, open cell content, and cell size was measured for foamsamples collected during each run. Density was measured according toASTM D792, open cell content was measured using gas pychnometryaccording to ASTM D285-C, and cell size was measured by averaging thecell diameters from scanning electron microscope (SEM) micrographs offoam sample fracture surfaces. SEM images are also used to observe thecell structure and qualitatively check for open cell content.

Table 2 shows data for examples 9 through 14, including the loading ofeach blowing agent in the formulation, the resin feed rate, melt flowindex of the resin, the expandable resin melt temperature, and thedensity, cell size, and open cell content of the resulting foamedproduct.

Comparative example 9 is typical for polystyrene foaming with HFC-134a,where the poor solubility and difficulties in processing tend to lead tohigher density foam with smaller size and more open cells.

Comparative examples 10 through 12 show results for foaming with3,3,3-trifluoropene (HFO-1243zf; TFP). At a loading of 8.5 wt % TFP theresulting foam had smaller cell size while comparative density toexamples 10 and 11.

In examples 13 and 14, blowing agent compositions of TFP (HFO-1243zf)and HCFO-1233zd permitted production of lower density foam thanachievable with TFP alone along with a beneficial enlargement in thecell size, where it was possible to produce closed-cell foam productwith cell sizes greater than 0.2 mm at densities less than 53 kg/m³.These foams would be useful as thermal insulating foams with improvedk-factor. The HCFO-1233zd was predominantly the trans-isomer.

Examples 15 and 16 were produced during using HFO-1234yf(2,3,3,3-tetrafluoroethane) as the only blowing agent. At a loading of5.7 wt % 1234yf, as shown in example 16, the foamed product had verysmall cell size, macrovoids, blowholes, high open cell content, andfrequent periods of popping at the die caused by undissolved blowingagent. Increasing the content of 1234yf made these problems worse. Forexamples 17 and 18, blowing agent compositions of HFO-1234yf andHCFO-1233zd permitted production of lower density foam than was producedusing the HFO-1234yf alone. The foamed samples of examples 17 and 18were of good quality, with few defects and produced without popping atthe die.

TABLE 2 Blowing Agent Loading Polystyrene Resin Foam Properties 134a TFP1234yf 1233zd Feed MFI T_(melt) Density Cell Size OCC Example (wt %) (wt%) (wt %) (wt %) (kg/hr) (g/10 min) (° C.) (kg/m³) (mm) (%) 9 6.4 — — —2.27 4.0 111 60.9 0.06 23 10 — 6.6 — — 2.27 11.0 114 57.6 0.11 <5 11 —7.2 — — 2.27 11.0 115 56.5 0.11 <5 12 — 8.5 — — 4.54 4.0 117 58.0 0.05<5 13 — 4.1 — 6.6 4.54 11.0 113 44.3 0.29 <5 14 — 6.5 — 3.4 4.54 11.0113 52.5 0.35 <5 15 — — 4.4 — 4.54 11.0 117 90.9 0.15 5 16 — — 5.7 —4.54 11.0 115 71.6 0.06 31.4 17 — — 4.2 4.3 4.54 11.0 114 55.2 0.12 <518 — — 4.8 5.0 4.54 11.0 113 53.5 0.08 <5

Examples 19-48

Extruded polystyrene foam was produced using a counter-rotating twinscrew extruder with internal barrel diameters or 27 mm and a barrellength of 40 diameters. The screw design was suitable for foamingapplications. The pressure in the extruder barrel was controlled with agear pump and was set high enough such that the blowing agent dissolvedin the extruder. The extruder die was an adjustable-lip slot die with agap width of 6.35 mm. Two grades of general purpose polystyrene was usedfor the extrusion experiments and fed to the extruder at an overall rateof 4.54 kg/hr (10 lb/hr). Blowing agents were pumped into thepolystyrene resin melt at a controlled rate using high pressure deliverypumps. In the extruder, the blowing agent mixed with and dissolved inthe resin melt to produce an expandable resin composition. Theexpandable resin composition was cooled to an appropriate foamingtemperature and then extruded from the die where the drop in pressureinitiates foaming. Talc was used as a nucleating agent at 0.5 wt % talcin polystyrene.

The density, open cell content, and cell size was measured for foamsamples collected during each run. Open cell content was measured usinggas pychnometry according to ASTM D285-C, and cell size was measured byaveraging the cell diameters from scanning electron microscope (SEM)micrographs of foam sample fracture surfaces. SEM images are also usedto observe the cell structure and qualitatively check for open cellcontent.

Examples 19 to 25 were produced using HFO-1243zf as the only blowingagent at loadings ranging from 4.1 to 8.5 wt %. Examples 22 and 23 areduplicates of examples 10 and 11 above. Example 25 is similar to example12 above; both were produced with 8.5 wt % HFO-1243zf, but example 25was found to be of better quality (fewer defects, lower density). Themelt temperature in example 25 was 125° C. while the melt temperature inexample 12 in the original application was 117° C. The results are shownin Table 3 and plotted in FIG. 1.

Examples 26 to 28 were produced using trans-HCFO-1233zd as the onlyblowing agent at loadings ranging from 8.6 to 11.7 wt %. The results areshown in Table 3 and plotted in FIG. 1.

Examples 29 to 37 were produced using blowing agent combinations of from38 wt %/o to 66 wt % HFO-1243zf and from 62 wt % to 34 wt %trans-HCFO-1233zd as the blowing agents. The total loading of blowingagent ranged from 8.2 to 12.5 wt %. Examples 33 and 34 duplicates ofexamples 13 and 14 above. The results are shown in Table 3 and plottedin FIG. 1.

Examples 38 to 48 were produced using blowing agent combinations of from33 wt % to 53 wt % HFO-1243zf, 28 wt % to 52 wt % trans-HCFO-1233zd, andfrom 13 wt % to 20 wt % carbon dioxide (CO2). The total blowing agentloading ranged from 7.6 to 11.3 wt %. The results are shown in Table 3and plotted in FIG. 1.

The blowing agent formulations for examples 19 to 48 are shown in Table3 along with the foam density. With the exception of Example 28, allfoams shown in Table 3 had an open cell content <10%. Example 28, blownusing 11.7 wt % trans-HCFO-1233zd, had an open cell content ˜13%. Withthe exception of Example 48, all foams shown in Table 3 had a cell size0.1 mm.

FIG. 1 shows a plot of total blowing agent content versus foam densityfor examples 19 to 48. As mentioned above, the data are divided intofour series: 1) Examples 19 to 25 for HFO-1243zf; 2) Examples 26 to 28for trans-HCFO-1233zd; 3) Examples 29 to 37 for combinations ofHFO-1243zf and trans-HCFO-1233zd (1243zf/1233zd); 4) Examples 38 to 48for combinations of HFO-1243zf, trans-HCFO-1233zd, and carbon dioxide(1243zf/1233zd/CO2). Trend lines for each series show the minimumdensity achieved for each blowing agent combination. The data shows thatusing the blowing agent combinations of 1243zf/1233zd or1243zf/1233zd/CO₂ permit production of low density foam over a widerrange of blowing agent loadings than either 1243zf or 1233zd alone. Forexample, examples 25 and 26 blown with approximately 8.5 wt % 1243zf and1233zd respectively. Examples 29-30 and 40-42, blown with 1243zf/1233zdand 1243zf/1233zd/CO2 respectively, are of significantly lower densitybut blown using about the same amount of blowing agent or less. Also,the foam of example 25 had a cell size <0.1 mm whereas all foams ofExamples 29-30 and 38-42 had cell sizes of from 0.1-0.3 mm. As shown inexamples 36 and 47, blown with 1243zf/1233zd and 1243zf/1233zd/CO₂respectively, it was possible to produce closed-cell foam with cellsizes >0.1 mm with density less than 40 kg/m³.

TABLE 3 Blowing Agent Composition Blowing Agent Loading Total Blowing1243zf 1233zd CO2 1243zf 1233zd CO2 Agent Loading Density Example (wt %)(wt %) (wt %) (wt %) (wt %) (wt %) (wt %) (kg/m³) 19 100%  — — 4.1 — —4.1 84.1 20 100%  — — 4.9 — — 4.9 70.2 21 100%  — — 5.8 — — 5.8 60.7 22100%  — — 6.6 — — 6.6 57.6 23 100%  — — 7.2 — — 7.2 56.5 24 100%  — —7.2 — — 7.2 51.9 25 100%  — — 8.5 — — 8.5 53.3 26 — 100%  — — 8.6 — 8.672.2 27 — 100%  — — 10.2 — 10.2 42.4 28 — 100%  — — 11.7 — 11.7 55.5 2965% 35% — 5.3 2.9 — 8.2 46.8 30 65% 35% — 5.3 2.9 — 8.2 50.6 31 49% 51%— 4.6 4.9 — 9.5 45.2 32 49% 51% — 4.6 4.9 — 9.5 43.2 33 49% 51% — 4.64.9 — 9.5 44.7 34 66% 34% — 6.5 3.4 — 9.9 52.5 35 38% 62% — 4.1 6.6 —10.7 44.3 36 45% 55% — 5.5 6.2 — 12.1 38.3 37 38% 62% — 4.8 7.7 — 12.541.8 38 52% 28% 20% 4.0 2.1 1.5 7.6 46.9 39 53% 29% 19% 4.2 2.3 1.5 8.048.1 40 53% 29% 18% 4.5 2.4 1.5 8.4 47.6 41 53% 29% 18% 4.5 2.4 1.5 8.442.9 42 33% 49% 17% 2.9 4.2 1.5 8.6 42.1 43 34% 50% 16% 3.0 4.5 1.5 9.143.2 44 43% 41% 16% 3.9 3.8 1.5 9.2 45.8 45 43% 41% 17% 3.9 3.8 1.5 9.241.9 46 34% 50% 16% 3.2 4.8 1.5 9.5 41.0 47 34% 51% 15% 3.6 5.3 1.5 10.439.8 48 35% 52% 13% 3.9 5.9 1.5 11.3 40.1

Examples 49-55 Batch Foaming

Batch-wise foaming experiments were conducted in 300 mL stainless steelautoclaves. For each example, approximately 6 gm of polystyrene powderwas loaded into the autoclave (except for Comp. Ex. 49, where 8 gm wasused). The autoclave was sealed and then evacuated to vacuum.Approximately 30-50 gm of total blowing agent was then charged to theautoclave; if multiple blowing agents were used, each was chargedseparately. The autoclave was then heated to achieve to the desiredtemperature and elevated pressure and then maintained at thattemperature for about 24 hours. To initiate foaming after the 24 hourwait period, the autoclave was rapidly degassed by opening a vent port.The autoclave was then opened and the foam sample removed and analyzed.Results are summarized in Table 4, which lists the blowing agentcombination used (with composition listed to within +/−1 wt %), weightof PS resin used, and the resulting foam density. In these examples,“1234ze(E)” refers to the trans-isomer of HFO-1234ze, “1234yf” refers toHFO-1234yf, “1233zd(E)” refers to the trans-isomer of HCFO-1233zd, and“245fa” refers to HFC-245fa. The results show that using the blowingagent combination of 1234ze(E) with 1233zd(E) permitted production oflower density foam, with a density <50 kg/m³, than using 1234ze(E) aloneand also lower than the combination of the 1234ze(E) with another HFO,in this example 1234yf, or the combination of the 1234ze(E) with an HFC,in this example 245fa, which both resulted in foam density that washigher than the 1234ze(E) alone.

Example 54 had a fine cell structure with an average cell size of <1 mm.

Comparative Example 51 had a coarser cell structure with an average cellsize of >1 mm.

TABLE 4 Batch Foaming of PS Foam Densi- Example Blowing Agent ty (kg/m³)Comp. Ex. 49 1234yf (100 wt %) 228 Comp. Ex. 50 1234ze(E) (100 wt %)75.0 Comp. Ex. 51 1233zd(E) (100 wt %) 29.7 Comp. Ex. 521234ze(E)/1234yf (50 wt %/50 wt %) 1.15 Comp. Ex. 53 1234ze(E)/245fa (50wt %/50 wt %) 86.7 Example 54 1234ze(E)/1233zd(E) (50 wt %/50 wt %) 38.6Example 55 1234ze(E)/1233zd(E) (74 wt %/26 wt %) 62.5

Although the invention is illustrated and described herein withreference to specific embodiments, it is not intended that the appendedclaims be limited to the details shown. Rather, it is expected thatvarious modifications may be made in these details by those skilled inthe art, which modifications may still be within the spirit and scope ofthe claimed subject matter and it is intended that these claims beconstrued accordingly.

1. A polystyrene foam product comprising a blowing agent compositioncomprising a combination of the hydrofluoroolefin1,3,3,3-tetrafluoropropene and the hydrochlorofluoroolefin1-chloro-3,3,3-trifluoropropene wherein said thermoplastic foam producthas a density less than about 63 kg/m³.
 2. The thermoplastic foamproduct of claim 1 where said 1-chloro-3,3,3-trifluoropropene comprisesgreater than 75% of the trans-isomer.
 3. The thermoplastic foam productof claim 1 wherein said blowing agent composition further comprises acoblowing agent selected from the group consisting ofhydrofluorocarbons, alkanes, carbon dioxide, methyl formate, inertgases, atmospheric gases, alcohols, ethers, fluorinated ethers,unsaturated fluorinated ethers, ketones, fluoroketones, water, andmixtures thereof.
 4. The thermoplastic foam product of claim 3 whereinsaid hydrofluorocarbon is selected from HFC-32, HFC-161, HFC-152,HFC-152a, HFC-143, HFC-143a, HFC-134, HFC-134a, HFC-125, HFC-245fa,HFC-365mfc, HFC-227ea, or mixtures thereof.
 5. The thermoplastic foamproduct of claim 3 wherein said hydrofluorocarbon is selected fromHFC-134a, HFC-152a, HFC-32, HFC-143a, HFC-245fa, or mixtures thereof. 6.The thermoplastic foam product of claim 3 wherein said alkane isselected from propane, butane, pentane, or hexane.
 7. The thermoplasticfoam product of claim 6 wherein said pentane is selected from n-pentane,cyclopentane, iso-pentane or mixtures thereof.
 8. The thermoplastic foamproduct of claim 3 wherein said alcohol is selected from ethanol,iso-propanol, butanol, ethyl hexanol, methanol, or mixtures thereof. 9.The thermoplastic foam product of claim 3 wherein said ether is selectedfrom dimethyl ether, diethyl ether, methylethyl ether, or mixturesthereof.
 10. The thermoplastic foam product of claim 3 wherein saidketone is selected from acetone, methyl ethyl ketone, or mixturesthereof.